I have a 04 3500 4x4 6 spd manual, stock, no mods at all. The problem that I am having is that it will not start without ether (previous owner started it that way, I have read about the horror stories and will not use it) or a pull/push start. The motor cranks over very stong with the key just does not start. It also only cranks for 20 seconds or so and then stops, not sure if that's normal? It has a new filter and fresh o-rings in the filter housing. The primer on top of the housing never gets very firm when pumping it to prime. Any help would be great.

I'd second the horror stories about ether, It's like using asprin to cure a broken arm; hides the symtoms but does nothing to cure the problem.

Have you looked at the primer screw fitting on top of the housing? Plastic, and apparantly often crack or split. Afteermarket metal ones are available (I forget where I saw them, though) or just get a new one from GM.

Thanks for the replies. I have replaced all the O-rings in the filter housing, including the one on the plastic plug. With a bad injector pump how is it that it will run if push/pull started and off of a shot of ether? I'm somewhat new to diesels so any input would be great.

The biggest problem with these engines is--- the did not put a fuel pump in the system. They used the CP3 to pull the fuel from the tank, through the filter and into the CP3 where it is pressurized and sent to the injectors. So any small leak from the tank to the engine, and the fuel will get air and allow the fuel to drain back to the tank, resulting a no start.

I have pressurized the fuel tank with the outlet of a shop vac-- be sure it is clean and place a rag over the hose to catch any dust. While pressurized, inspect the entire fuel system, filter, WIF sensor, around the hoses and lines. You can use shop air but keep the pressure below 10 lbs. Hope this helps.

Thanks for the replies. I have replaced all the O-rings in the filter housing, including the one on the plastic plug. With a bad injector pump how is it that it will run if push/pull started and off of a shot of ether? I'm somewhat new to diesels so any input would be great.

I would get a Shop-Vac and pressurize the tank by blowing into the filler neck. Look for fuel leaks and fix any you find. My first suspect would be the gasket around the fuel filter not being seated, next the WIF sensor. If it's a leak in the fuel supply, the pressure on the fuel tank will reveal it.

The CP3 has to put a minimum amount of fuel pressure on the injectors before they'll open (IIRC, something like 5000psi). In a worse case scenario, if the second stage of the CP3 is the problem, it can be diagnosed by low fuel pressure from the CP3. Best case scenario, the Fuel Pressure Regulator is the problem and the CP3 is good - a rail pressure test will reveal it.

Sounds like a problem on the high pressure side. More than likely an injector returning too much fuel or leaking past the needle keeping the CP3 from building pressure. Ether will get it spinning faster and allow it to build enough pressure to fire.

Register Now

In order to be able to post messages on the Chevy and GMC Duramax Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:

Password

Please enter a password for your user account. Note that passwords are case-sensitive.

Password:

Confirm Password:

Email Address

Please enter a valid email address for yourself.

Email Address:

Log-in

User Name

Remember Me?

Password

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.

AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.